IMO; (few things, apologise for the crappy drawing)
1 You can add a few small 'splits' in the side profile. This isn't a brillant drawing of it, natch. Basically a region which is slightly indented and breaks it up. It is very close-in detail (Depending on how you do it) but IMO it's more efficient for the distance than gatlings, and looks better from in-cockpit
2 I'd consider rounding this out a bit. The frontal profile is basically a cube, which IMO makes the whole thing seem less detailed.
3 This is just a flat box with stuff stuck on it. I'm not sure what it's for, but you can surely add something to it; round it off, add surface vents or access hatches (for maintenance), etc. Or the all-important rearm dock. With HTL, there's no real sense in not physically modelling the rearm dock IMO (except for Volition remodels, where you can argue it's not on the original).
4 Flatten the ends. Just extrude a tiny bit and flatten that if you want it to look blunt. Same goes for the tails. Also, you could 'stagger' them a bit by subdividing, etc; tweak around from the boring old triangle shape.
5 Add some rounding to the gun holders. As it stands they're just plain old boxes; add some details, perhaps to make it obvious how the maint guys would insert and remove the primaries as selected at startup.
